The practice of pranayama works mainly with pranamaya kosha.
This kosha is made up of 5 major pranas called pancha pranas: prana, apana, samana, udana and vyana.
Prana is responsible for the intake of impressions and ideas. Also this prana is responsible for inhalation or to draw the air into the system. This Prana energizes all the koshas and is active all the time. Heart and lungs are directly controlled and regulated by this prana. It pervades the region from heart up to throat centre. When the force of prana is strong and flowing uninterruptedly, purer qualities of the heart, such as strength, courage, enthusiasm also love, compassion, joy and other moral qualities are expressed.
Apana is a downward moving force which lies from the navel to the pelvic but also sometimes effects up to the toes (example: sciatica pain).
This is also considered the vital prana and is responsible for the purification.
So the feelings of urination, evacuation, expulsion of gas,… occurs because of prana.
The function of the kidneys, bladder, bowels, excretory and reproductive organs is directly governed and regulated by this prana.
Problems like constipation, diarrhea, piles, fistula, hemorrhoids, some sexual disorders and period issues, lower back pains are caused because of imbalance of apana.
The place of samana is between of the diaphragm and the navel.
The word samana is derived from the root saman meaning “equal” or “balanced”.
All the organs those are participating in the digestion system are controlled, regulated and influenced by samana prana. So, samana is responsible for the digestion, assimilation, absorption of the food, and the metabolism.
Problems related to indigestion, diarrhea, excess of hunger or less hunger (no appetite) and other problems related to stomach, laver, small intestine, pancreas occurs because of samana prana.
Udana is upward moving force and especially lies from the throat to the top of the head and others extremities (arms and legs).
The function of all the sensory organs like eyes, nose, tongue, ears, and skin is controlled, regulated and influenced by this prana.
So, issues related to vision, smell, earing and taste occur by the imbalance of this prana.
The center of Udana prana is actually the throat. So, thyroid gland is governed by this prana. Also the voice quality (or communication) depends on it. People having strong udana prana always are great influencers in the world. They have the magic in their voice.
Vyana, the fifth prana, pervades the whole body and acts as a reserve force in the body. It helps all the other pranas when they need an extra boost/energy. In the body, it works as an immunity power.
When any other prana becomes weak, this prana supports to other but when this prana becomes weak, body falls sick.
This prana is also considered for the necessity of existence of the life. When someone pass away, still this prana lies in the body for few minutes after the declaration of the doctor.